Semiconductor device and method for manufacturing same

A method for manufacturing a semiconductor device, the method comprising:

• a step (A) of forming a thin film transistor by forming, on a substrate, a gate electrode, a gate insulating layer, an oxide semiconductor layer, and a source electrode and a drain electrode including a copper layer;
• an oxidation treatment step (B) of performing an oxidation treatment on at least a channel region of the oxide semiconductor layer, thereby increasing an oxygen concentration of a surface of the at least one portion to be the channel region and oxidizing a surface of the source electrode and the drain electrode to form a copper oxide film;
• a step (C) of forming an interlayer insulating layer so as to cover the thin film transistor and to be in contact with the channel region;
• a contact hole formation step (D) of forming a first contact hole in a portion of the interlayer insulating layer that is located over the drain electrode, thereby exposing the copper oxide film;
• a step (E) of removing a portion of the copper oxide film that is exposed through the first contact hole using a chelate cleaning method, thereby exposing the copper layer;
• and
• a step (F) of forming a transparent conductive layer so that the transparent conductive layer is in direct contact with the copper layer exposed in the first contact hole.